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Rare variable star 39 EP

25Rho Per

RA 46.2940° · Dec 38.8403° · star

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Score breakdown

· 7 badges
39 pts · Rare
Rare 50 pts → Epic
  • Naked-eye visible +8
  • Deep red star +8
  • Giant star +6
  • Variable star +5
  • Cool red M-type star +5
  • Gently variable +4
  • A named variable star +3
Total score 39

11 more points to reach Epic.

Badges

  • Variable star · +5
  • Naked-eye visible · +8
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8
  • Gently variable · +4
  • A named variable star · +3

Trivia

What it actually is

  • Spectral class. Its spectrum reads M3IIIvar — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.
  • It changes. This star does not hold still: its brightness rises and falls on a rhythm of hours, days or years, either pulsing in size or being eclipsed by a companion.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 3.3 you can see it with your own eyes from a dark site, over in Perseus.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Properties

absmag
-1.553
bv
1.528
constellation
Per
dist ly
307.6943
luminosity
364.0827
mag
3.32
name
25Rho Per
spect
M3IIIvar
var amplitude
0.2
var designation
Rho
var max
3.262
var min
3.462

About 25Rho Per

25Rho Per is a rare variable star. It lies about 307.7 light-years from Earth, sits in the constellation Per, shines at apparent magnitude 3.32 and has spectral type M3IIIvar.

Its spectrum reads M3IIIvar — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for 25Rho Per in the constellation Per. At apparent magnitude 3.32, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 25Rho Per is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why 25Rho Per is a rare variable star

25Rho Per scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 7 science badges — Variable star, Naked-eye visible, Cool red M-type star, Giant star, Deep red star, Gently variable and A named variable star — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.